1. Field of the Invention
The present invention generally relates to a method of cooling an encapsulated type housing, and a cooling apparatus for an encapsulated type housing. More specifically, the present invention is directed to a low-cost cooling method/cooling apparatus for an encapsulated, or sealed type housing, while a cooling efficiency and a waterproof characteristic are increased, and a total number of components is minimized.
2. Description of the Related Art
Conventionally, for instance, Japanese Laid Open Patent Application (JP-A-Heisei 5-102687) and Japanese Laid Open Patent Application (JP-A-Heisei 7-113589) describe cooling apparatuses for the sealed, or encapsulated type housings such as a sealed type cabinet used for a radio communication appliance used in an outdoor field. That is, these patent applications describe the heatpipe type cooling apparatuses equipped with the heat collecting fins installed inside the housings, and also the heat radiating fins installed outside the housings.
FIG. 1A is a front view for showing the conventional cooling apparatus for the sealed, or encapsulated type housing. FIG. 1B is a sectional view for showing this cooling apparatus, taken along a line III--III of FIG. 1A. FIG. 2 is a sectional view for representing this cooling apparatus, taken along a line II--II of FIG. 1A.
In this conventional cooling apparatus, three sets of heatpipes 5 are provided on the upper unit of the housing. The operating temperatures of these heatpipes 5 are different from each other. The heat collecting fin 4 is provided on the inside of the housing 1 of the heatpipes 5, whereas the heat radiating fin 4a is provided on the outside of the housing 1.
This heatpipe 5 is constructed in the form of a heatpipe assembly for assembling the heat collecting fin 4, the heat radiating fin 4a, the heat insulating material 1a, and the mounting plate 7 in an integral form. This heatpipe assembly is inserted into the housing 1 though a hole (not shown in detail). This hole is formed in the upper unit of the housing 1, and has a shape corresponding to the shape of the heat insulating material 1a of this heat pipe assembly. The mounting plate 7 of the heatpipe assembly is screwed on this housing 1. Furthermore, for example, this mounting plate 7 may be fixed by filling properly selected resin into a space formed in the hole. The sun-shade 6 is provided on the portion of this heatpipe assembly located at the outside from the housing 1.
The above-described conventional cooling apparatus for the sealed type housing has the following problems. That is, since the heat radiating fin 4a is exposed to the outside portion of the sealed type housing 1, this heat radiating fin 4a may absorb direct heat and/or radiation heat given from the sun. As a result, the internal temperature of this housing 1 would be conversely increased, contrary to its essential function of this heat radiating fin 4a.
Moreover, the sealing distance between the housing 1 and the heat radiating fin 4a which is largely exposed to the outside of the housing 1 is very long, resulting in deteriorations of the water-proofing characteristics and drip-proofing characteristics of the housing 1. In addition, since the size of the above-described hole is large, this may also cause the water-proofing/drip-proofing problems of the cooling apparatus. This hole formed in the upper unit of the housing 1 is employed to insert the heatpipe assembly into the housing 1.
Also, this conventional cooling apparatus owns another problem. That is, the expensive heatpipe type cooling device is required. In addition, since a very large number of structural components are required in this heatpipe type cooling device, and also a total number of assembling stages for the heatpipe type cooling device is needed. Therefore, total cost of the cooling apparatus would be increased.
On the other hand, Japanese Laid Open Utility Model Application (JPU-A-Heisei 7-41262) discloses the following cooling construction. That is, this disclosed cooling construction is equipped with the heat radiating fin 2 of the heat pipe 1, and the air duct 12. This heat radiating fin 2 is located outside the housing 11 which contains the heat radiating source 10. The air duct 12 is made in the continuous shape, and is used to exhaust air conducted thereinto from the housing 11 by contacting all amounts of this conducted air to the heat radiating fin 2. This air duct 12 is installed outside the housing 11. The heat radiating fin 2 is arranged at the upper portion of the penetration unit of the side wall of this housing 11.
However, this conventional heatpipe type cooling structure could not also solve the above-explained problems.
Further, Japanese Laid Open Patent Application (JP-A-Heisei 7-83582) discloses the below-mentioned cooling apparatus. That is, in this conventional cooling apparatus, the zig-zag type narrow-tube heatpipe 2 is provided to penetrate the separator plate 1. Both sides of the surface of this separator plate 1 are routed in the zig-zag path, so that the pin-fin group having a needle-point-holder shape is formed.
However, this conventional cooling apparatus could not also solve these problems.